linux-kernel - Re: [syzbot] [hfs?] kernel BUG in hfs_new

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Message-ID: <6907a5c1.a70a0220.37351b.000d.GAE@google.com>
Date: Sun, 02 Nov 2025 10:41:05 -0800
From: syzbot <syzbot+17cc9bb6d8d69b4139f0@...kaller.appspotmail.com>
To: jkoolstra@...all.nl, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [hfs?] kernel BUG in hfs_new_inode

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
VFS: Busy inodes after unmount (use-after-free)

VFS: Busy inodes after unmount of loop0 (hfs)
------------[ cut here ]------------
kernel BUG at fs/super.c:652!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 6456 Comm: syz-executor Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:generic_shutdown_super+0x2bc/0x2c0 fs/super.c:650
Code: 03 42 80 3c 28 00 74 08 4c 89 f7 e8 1e 14 f3 ff 49 8b 16 48 81 c3 c8 07 00 00 48 c7 c7 c0 ce f8 8a 48 89 de e8 c5 89 f9 fe 90 <0f> 0b 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f
RSP: 0018:ffffc90004b07d20 EFLAGS: 00010246
RAX: 000000000000002d RBX: ffff888032f747c8 RCX: 49dab819c755c300
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 1ffff110065ee91a R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff52000960f49 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffffff8d9ce5e0 R15: ffff888032f748d0
FS:  00005555664c8500(0000) GS:ffff888126cbf000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055f7155aa950 CR3: 0000000031628000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 kill_block_super+0x44/0x90 fs/super.c:1722
 deactivate_locked_super+0xbc/0x130 fs/super.c:473
 cleanup_mnt+0x425/0x4c0 fs/namespace.c:1327
 task_work_run+0x1d4/0x260 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xe9/0x130 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9992a402f7
Code: a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 a8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffcd2add748 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f9992ac1d7d RCX: 00007f9992a402f7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffcd2add800
RBP: 00007ffcd2add800 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffcd2ade890
R13: 00007f9992ac1d7d R14: 00000000000297ad R15: 00007ffcd2ade8d0
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:generic_shutdown_super+0x2bc/0x2c0 fs/super.c:650
Code: 03 42 80 3c 28 00 74 08 4c 89 f7 e8 1e 14 f3 ff 49 8b 16 48 81 c3 c8 07 00 00 48 c7 c7 c0 ce f8 8a 48 89 de e8 c5 89 f9 fe 90 <0f> 0b 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f
RSP: 0018:ffffc90004b07d20 EFLAGS: 00010246
RAX: 000000000000002d RBX: ffff888032f747c8 RCX: 49dab819c755c300
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 1ffff110065ee91a R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff52000960f49 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffffff8d9ce5e0 R15: ffff888032f748d0
FS:  00005555664c8500(0000) GS:ffff888126cbf000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055f7155aa950 CR3: 0000000031628000 CR4: 00000000003526f0


Tested on:

commit:         691d401c Merge tag 'spi-fix-v6.18-rc3' of git://git.ke..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10baee14580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=72f4d1bb6e3e45a2
dashboard link: https://syzkaller.appspot.com/bug?extid=17cc9bb6d8d69b4139f0
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15cebf34580000